JSON Class
The JSON module adds support for serializing JavaScript objects into JSON strings and parsing JavaScript objects from strings in JSON format.
The JSON namespace is added to your YUI instance including static methods Y.JSON.parse(..) and Y.JSON.stringify(..).
The functionality and method signatures follow the ECMAScript 5 specification. In browsers with native JSON support, the native implementation is used.
The json module is a rollup of json-parse and
json-stringify.
As their names suggest, json-parse adds support for parsing
JSON data (Y.JSON.parse) and json-stringify for serializing
JavaScript data into JSON strings (Y.JSON.stringify). You may choose to
include either of the submodules individually if you don't need the
complementary functionality, or include the rollup for both.
Methods
- _revive
- dateToString static deprecated
- escapeException
- parse static
- stringify static
Properties
- _BRACKETS
- _ESCAPES
- _UNICODE_EXCEPTIONS
- _UNSAFE
- _VALUES
- charCacheThreshold static
- Native
- useNativeParse static
- useNativeStringify static
Events
Methods
_revive
_revive
(
-
data
-
reviver
)
MIXED
private
Traverses nested objects, applying a reviver function to each (key,value) from the scope if the key:value's containing object. The value returned from the function will replace the original value in the key:value pair. If the value returned is undefined, the key will be omitted from the returned object.
Parameters:
| name | type | flag | description |
|---|---|---|---|
data
| MIXED | Any JavaScript data | |
reviver
| Function | filter or mutation function |
Returns:
The results of the filtered data
dateToString
dateToString
(
-
d
)
String
deprecated
static
Serializes a Date instance as a UTC date string. Used internally by stringify. Override this method if you need Dates serialized in a different format.
Parameters:
| name | type | flag | description |
|---|---|---|---|
d
| Date | The Date to serialize |
Returns:
stringified Date in UTC format YYYY-MM-DDTHH:mm:SSZ
escapeException
escapeException
(
-
c
)
String
private
Replaces specific unicode characters with their appropriate \unnnn format. Some browsers ignore certain characters during eval.
Parameters:
| name | type | flag | description |
|---|---|---|---|
c
| String | Unicode character |
Returns:
the \unnnn escapement of the character
parse
parse
(
-
s
-
reviver
)
MIXED
static
Parse a JSON string, returning the native JavaScript representation.
Parameters:
| name | type | flag | description |
|---|---|---|---|
s
| String | JSON string data | |
reviver
| Function | (optional) function(k,v) passed each key value pair of object literals, allowing pruning or altering values |
Returns:
the native JavaScript representation of the JSON string
stringify
stringify
(
-
o
-
w
-
ind
)
String
static
Converts an arbitrary value to a JSON string representation.
Objects with cyclical references will trigger an exception.
If a whitelist is provided, only matching object keys will be included. Alternately, a replacer function may be passed as the second parameter. This function is executed on every value in the input, and its return value will be used in place of the original value. This is useful to serialize specialized objects or class instances.
If a positive integer or non-empty string is passed as the third parameter, the output will be formatted with carriage returns and indentation for readability. If a String is passed (such as "\t") it will be used once for each indentation level. If a number is passed, that number of spaces will be used.
Parameters:
| name | type | flag | description |
|---|---|---|---|
o
| MIXED | any arbitrary value to convert to JSON string | |
w
| Array | Function | (optional) whitelist of acceptable object keys to include, or a replacer function to modify the raw value before serialization | |
ind
| Number | String | (optional) indentation character or depth of spaces to format the output. |
Returns:
JSON string representation of the input
Properties
_BRACKETS
RegExp
private
Third step in the safety evaluation. Regex used to remove all open square brackets following a colon, comma, or at the beginning of the string.
_ESCAPES
RegExp
private
First step in the safety evaluation. Regex used to replace all escape sequences (i.e. "\", etc) with '@' characters (a non-JSON character).
_UNICODE_EXCEPTIONS
RegExp
private
Replace certain Unicode characters that JavaScript may handle incorrectly during eval--either by deleting them or treating them as line endings--with escape sequences. IMPORTANT NOTE: This regex will be used to modify the input if a match is found.
_UNSAFE
RegExp
private
Final step in the safety evaluation. Regex used to test the string left after all previous replacements for invalid characters.
_VALUES
RegExp
private
Second step in the safety evaluation. Regex used to replace all simple values with ']' characters.
charCacheThreshold
Number
static
Number of occurrences of a special character within a single call to stringify that should trigger promotion of that character to a dedicated preprocess step for future calls. This is only used in environments that don't support native JSON, or when useNativeStringify is set to false.
So, if set to 50 and an object is passed to stringify that includes strings containing the special character \x07 more than 50 times, subsequent calls to stringify will process object strings through a faster serialization path for \x07 before using the generic, slower, replacement process for all special characters.
To prime the preprocessor cache, set this value to 1, then call
Y.JSON.stringify("(all special characters to
cache)");, then return this setting to a more conservative
value.
Special characters \ " \b \t \n \f \r are already cached.
Default:
100
Native
Object
private
Alias to native browser implementation of the JSON object if available.
useNativeParse
Boolean
static
Leverage native JSON parse if the browser has a native implementation. In general, this is a good idea. See the Known Issues section in the JSON user guide for caveats. The default value is true for browsers with native JSON support.
Default:
true
useNativeStringify
Boolean
static
Leverage native JSON stringify if the browser has a native implementation. In general, this is a good idea. See the Known Issues section in the JSON user guide for caveats. The default value is true for browsers with native JSON support.
Default:
true